1Begin by preparing the chiles. Remove the stems and seeds from the Guajillo chiles and Ancho chiles. Place them in a heatproof bowl and cover with very hot water. Let them rehydrate for 20 minutes, until softened.
2While the chiles rehydrate, finely dice the White onion and mince the Garlic. Peel and dice the Potatoes and Carrots into small, uniform cubes.
3Drain the rehydrated Guajillo chiles and Ancho chiles, reserving a small amount of the soaking liquid. In a blender, combine the drained chiles, Roma tomatoes, half of the diced White onion, and the minced Garlic. Add a splash of the reserved chile soaking liquid if needed to help blend, and process until a smooth sauce is formed.
